Answer:-

Step 1:

\[\begin{array}{cc}
\ce{H3C\phantom{…………………………}}\ce{H\phantom{………}}\\
|\phantom{…………………………….}|\phantom{………}\\
\phantom{.}\ce{C = O + CH3 – OH ⇌[dry HCl][dil.HCl] H3C – C – OCH3}\\
\phantom{.}|\phantom{…………………………….}|\phantom{………}\\
\phantom{..}\ce{\underset{Acetaldehyde}{H}}\phantom{………………….}\ce{\underset{Hemiacetal (unstable)}{OH}}\phantom{……..}
\end{array}\]

Step 2:

\[\begin{array}{cc}
\ce{H\phantom{……………………………….}}\ce{H\phantom{………}}\\
|\phantom{………………………………..}|\phantom{………}\\
\ce{H3C – C – OCH3 + CH3 – OH ⇌[dry HCl][dil.HCl] H3C – C – OCH3 + H2O}\\
|\phantom{………………………………..}|\phantom{………}\\
\ce{\underset{Hemiacetal (unstable)}{H}\phantom{………………..}}
\ce{\underset{Acetaldehyde dimethyl acetal (stable)}{OCH3}\phantom{.}}
\end{array}\]

The conversion of acetaldehyde into acetaldehyde dimethyl acetal involves the reaction of acetaldehyde with methanol in the presence of an acid catalyst. Here’s the reaction:

Conversion of Acetaldehyde to Acetaldehyde Dimethyl Acetal:

In this reaction:

• Acetaldehyde (CH3CHO) reacts with two molecules of methanol (CH3OH).

• An acid catalyst (often sulfuric acid, H2SO4) is typically used to facilitate the reaction.

• The product formed is acetaldehyde dimethyl acetal (CH3CH(OMe)2).

• Water (H2O) is also produced as a byproduct of the reaction.

Acetaldehyde dimethyl acetal is a common acetal compound formed by the reaction of aldehydes or ketones with methanol in the presence of acid. It is used as a protecting group in organic synthesis and as a solvent.